An anonymous donor wants to increase the number of bison in the iconic herd at Golden Gate Park — but before any more bovids arrive here, their home needs a revamp.

There are five remaining bison in the paddock in the park that sits west of Spreckles Lake on John F. Kennedy Drive.</p>

The Recreation and Park Department has made upgrades to the site in recent years, spending $1.2 million on the irrigation system and expanding the open space from 7 acres to 12 acres.

But now that an anonymous donor wants to replenish the herbivores’ population, the department needs to find funding to bring the corral area up to federal standards.

In December, when Jim Lazarus was president of the Recreation and Park Commission he told commissioners their pending gift could slip out of their hands if they didn’t move forward quickly, according to documents.

And he’s still saying the same thing, but has since resigned from the commission.

“I don’t know how much time we have,” he said. “The thing is we’ve already lost a few from old age.”

The care of the bison is split: Zookeepers feed them their hay and fresh produce while Rec and Park gardeners maintain the pasture.

Veterinarians at the San Francisco Zoo usually euthanize the bison when they reach their late 20s. The remaining females — ages 18 to 26 — are not getting any younger.

Chief Veterinarian Dr. Jacqueline Jencek of the San Francisco Zoo, who tends to the welfare of the bison, said it would not be her decision, but if Rec and Park were to eventually bring in more bison, they should be young ones.

“Clinically all five are doing great right now,” Jencek said. “But bringing in others that are full grown, I’d be worried they could really hurt our old ladies. They’d have to be younger, kinder and gentler.”

Some preservationists simply find the animals, which first came to the park in the late 1800s, charming.

“They’re part of the park’s history.

There used to be a menagerie. There used to be a lot of different animals,” said Katherine Howard of the Golden Gate Park Preservation Alliance. “I think they’re charming.”